The people of Ukraine have told the world what their best interest is: removing Russian soldiers from their land, by force if necessary.
The US is only interested in Ukraine when their goals align. Everyone knows this, including most Americans and most Ukrainians.
However, it turns out that US and Ukrainian goals do, in fact, align. The US isn’t “using” Ukraine any more than Ukraine is “using” the US. They are openly cooperating to achieve a common interest.